Controls, indicating meters, chart recorders and other types of electrical equipment controls are typically installed on the surface of control equipment enclosures. Control equipment enclosures enable switches and meters to be arranged in an orderly and safe fashion on the exterior surface of the enclosure. Since these controls are on the surface of the control equipment enclosure, they are exposed to the environment where the control equipment enclosure is located. These controls can be damaged by water leaks, rain, or dirt. The controls can be inadvertently operated or broken when bumped.
One means used to protect electrical equipment controls is locating the controls and indicators inside the equipment enclosure. This places the indicators out of view and requires the equipment enclosure be opened to view the indicators or operate the controls. This has not been a satisfactory solution for frequently accessed indicators and controls.
Another means to protect electrical equipment controls and indicators is mounting viewing windows on the surface of the equipment enclosure over selected controls and indicators. These viewing windows are typically hinged to allow access to the controls within the viewing window. These viewing windows provide protection from physical damage and inadvertent operation from bumping and protection from dust, falling dirt and dripping noncorrosive liquids. However, these viewing windows have not protected the enclosed indicators and controls from corrosion, windblown dust and rain, splashing water and hose-directed water.
Existing viewing windows can meet the requirements of the National Electrical Manufacturers Association (NEMA) standards for Enclosures for Electrical Equipment (1000 Volts Maximum) Publication No. 250 for Type 12 enclosures. This provides indoor protection from dust, falling dirt and dripping noncorrosive liquids. These viewing windows have not met the requirements for Type 4 and Type 4X enclosures which provide indoor and outdoor protection from corrosion, wind blown dust and rain, splashing water and hose-directed water.